Intermittent Fasting and Longevity

One source of confounding could be other religious rules. People who follow Mormon teachings about fasting to the letter are more likely to follow other Church doctrines as well, and indeed regular fasters smoked far less often and were much more likely to be abstainers. These two factors were also taken into account, and the higher life expectancy still remained statistically. What was not taken into account, however, was the composition of the diet. In addition to monthly fasting, the Mormon Church recommends eating mainly whole grains, fruits, and vegetables and eating meat only “sparingly.”a Therefore, it is unclear to what extent the higher life expectancy of fasters is due to the quality of their diet or to the regular reduction in the quantity of their diet. The only way to establish cause and effect is to study intermittent fasting, which remarkably was already done in the 1950s.

Motivated by existing data on life extension through calorie restriction in laboratory rats, researchers divided 120 nursing home residents in Madrid into two groups. Sixty of them continued eating as usual, and the other 60 were put on modified intermittent fasting for three years. Details on this study and its results can be found at see.nf/fastinglongevity, but essentially it is cited as evidence that calorie restriction improves health and may even extend lifespan, since there were about twice as many deaths and hospitalizations in the control group. But as I explain in the video, substantial reservations are warranted.

Fasting-Mimicking

Instead of 5 : 2

how about a 25 : 5 diet, meaning five days per month of “afasting-mimicking“a? Longevity researcher Valter Longo developed a 5-day eating plan intended to simulate the metabolic effects of fasting, with little protein, sugar, and calories, and with no animal protein and no animal fat at all. By basing the plan on plant-based eating, Longo hoped to be able to lower levels of the cancer-promoting growth hormone IGF-1, which is associated with the consumption of animal protein. After three cycles of his 5-days-per-month program, that was achieved, and not only that, but inflammation markers also fell. The pros and cons can be found at see.nf/52fmd.

Longo founded a company to market his eating plan, but reportedly donates the profits to his nonprofit research foundation, which must be credited to him. The entire diet (“aProLon“a) seems to consist mainly of a few soup mixes made from dried vegetables, mushrooms, and tomatoes, herbal teas like hibiscus and chamomile, kale chips, nut-based energy bars, a DHA supplement mostly from algae, and a multivitamin tinged with vegetable powder. But why spend $50 a day on a few processed snacks when you could instead simply eat a few hundred calories of real vegetables?

Time-Restricted Eating and Longevity

What should we make of fasting a little bit every day? The reason blood is drawn in the morning on an empty stomach is that every meal can throw systems out of balance and raise levels of certain disease biomarkers such as blood sugar, insulin, cholesterol, and triglycerides, but not even one in ten Americans manages to go twelve hours a day without eating. Would it be good to give the body a longer break?

Time-restricted eating means fasting for at least 12 but no more than 24 hours. In see.nf/tre I present evidence that early time-restricted eating

that is, a narrow eating window shifted to the early part of the day

brings a number of metabolic benefits. As I describe in see.nf/earlytre, for example, participants randomized to eat only within a 6-hour window that ended before 3 p.m. lowered their blood pressure, oxidative stress, and insulin resistance, even though it was ensured that all participants maintained their weight. The average drop in blood pressure was extraordinary: from 123/82 to 112/72 in only five weeks, comparable to the effect of a strong blood pressure medication.

As I report at see.nf/earlytre, studies suggest that long overnight fasting combined with reduced food intake in the evening can reduce cancer risk and recurrence risk. It may also play a role in the health of perhaps the longest-living population in the world, the Seventh-day Adventists in California. They are lean, vegetarian, eat nuts, exercise, and do not smoke, and live about ten years longer than the general population. Their longer life expectancy is attributed to this healthy lifestyle, but there is another less well-known factor that could play a role. Originally, Adventist teachings included eating only two large meals a day, breakfast and lunch, and fasting in the evening and at night. Today only one in ten reports eating two meals per day, but for most (63 percent) breakfast or lunch is the largest meal of the day.

A study of older Italians found that people whose eating window was tighter than ten hours per day had a 72 percent lower risk of cognitive impairment. However, that applied only to those who ate early in the day (that is, they did not skip breakfast). In general, shifting food intake to the morning

eat breakfast like a king, lunch like a prince, and dinner like a pauper, or skip it altogether

brings cardiovascular benefits, whereas the same eating window, when shifted toward the evening and breakfast is skipped, can have no effects or negative effects.

Do Not Try This at Home

What is the benefit of regularly fasting longer? Advocates describe fasting as a detoxification process, but part of what they are detoxifying their bodies of is vital vitamins and minerals. In see.nf/fastingsafety I address the very real risks of prolonged fasting. Contrary to the widespread idea that the heart muscle is especially spared during fasting, the heart appears to suffer a similar loss of muscle. The most dangerous part seems to be breaking the fast. After World War II, one in five of the starving Japanese prisoners of war tragically died after being released. Today, it is called “aRefeeding syndrome“a when resuming a normal diet leads to multi-organ failure.